Abstract

Landscape Ecol (2017) 32:2297–2310 https://doi.org/10.1007/s10980-017-0569-9 RESEARCH ARTICLE Holding the line: three decades of prescribed ﬁres halt but do not reverse woody encroachment in grasslands . . . Jesse E. D. Miller Ellen I. Damschen Zak Ratajczak Mutlu Ozdog˘an Received: 22 December 2016 / Accepted: 7 September 2017 / Published online: 18 September 2017 Springer Science+Business Media B.V. 2017 Abstract that result in thresholds, beyond which its reversal is Context Encroachment of woody vegetation repre- difﬁcult. sents a signiﬁcant global threat to biodiversity in Objectives We ask what impact reintroducing fre- grasslands, but practices used to reverse encroachment quent ﬁre has on encroachment relative to the are rarely evaluated comprehensively. Several factors inﬂuences of landscape context and historical vegeta- may drive encroachment, such as land use history, tion. We investigate whether woody cover frequency alteration of disturbance regimes, and local environ- distributions suggest that feedbacks reinforce ment, but their relative importance is poorly under- encroachment after a threshold of woody cover is stood. Another complicating factor is that surpassed. encroachment may proceed via positive feedbacks Methods We analyze aerial photos in glade grass- lands in Missouri, USA, to assess encroachment patterns over a 75-year period. Fire was excluded from this